This invention relates to casting in general and, more particularly, to a method of making a mold for casting and a method of casting a pump impeller or the like in one piece.
Various methods have been developed for casting impellers and other similar devices which include a curved blade structure. Casting methods are described in the Metals Handbook, 8th Edition, Volume 5, entitled Forging and Casting, particularly at page 222 et seq. In it are disclosed a number of methods of casting devices such as impellers, wheels having angular vanes and the like. Of particular interest is the disclosure on page 223 of the use of flexible rubber patterns. These are noted as being useful in making molds for casting wheels having angular vanes. As described, the use of flexible rubber patterns permits patterns having as much as 30.degree. negative drift to be withdrawn without damaging molds that have high green strength.
Despite recognition of the usefulness of flexible molds, the majority of the teaching relating to the construction of impellers describes the use of separate vane cores when making a device of this nature. Obviously, the use of a plurality of such cores makes the process much more difficult. It, thus, becomes evident that there is a need for an improved method of casting an impeller in one piece.